Just the Facts, Ma'am: Arguing for Logic on the LSAT

What do lawyers do? They argue. They make statements and support them with evidence in order to convince a judge or jury that they're right or that their opponents are wrong. They read statutes and cases and briefs looking for tidbits of information that they can use to prove that their side is right or the other side is wrong — all under an intense time crunch.

What don't lawyers do? They don't argue from personal conviction or emotion. They don't structure their arguments based on their own feelings, but on the facts and the laws. They don't always get to choose the side they represent, which occasionally results in a lawyer supporting a side that she personally believes should lose a case.

The LSAT Logical Reasoning section is designed to test your ability to do many of these lawyerly tasks.

Starting off with an argument

In every Logical Reasoning argument the author states some conclusion and attempts to support it with evidence. Your job is to identify this conclusion, figure out how the author is supporting it, and then determine why it's successful or not.

Here's an example: "My house is full of bees. I need to call an exterminator." What's the conclusion of this argument? I need to call an exterminator. What evidence is used to justify this conclusion? My house is full of bees.

This basic statement, simple though it is, could become the basis for a variety of Logical Reasoning-style questions. For example, what assumptions does this statement make? It assumes that an exterminator can eradicate bees in a house. What information could strengthen the conclusion? Maybe something like "exterminators are specialists in ridding houses of insect pests." What information could weaken the conclusion? How about a statement such as "Ordinary exterminators don't handle bee swarms, and recommend that customers call animal control specialists to take care of them."

Logical Reasoning questions, like all LSAT questions, include all the information you need to answer them correctly. That means you don't have to be an expert in any esoteric topic — say, bees or exterminators — to answer them. That doesn't mean, however, that you don't have to understand what they're talking about. Logical Reasoning questions presume a fairly high level of reading proficiency and vocabulary; you have to be a skilled reader in order to understand the arguments well enough to work with them. So you should still leave your preconceived notions about a subject at home, but you should definitely keep thinking actively and put your vocabulary and reading skills to work.

Most Logical Reasoning questions are a bit longer than this example, and they're usually not as straightforward. At heart, though, they're not that different. Every one offers a proposition and supports it with evidence. The proposition may be right or wrong, and the evidence may or may not support it, but the basic structure doesn't change.

Here's an actual Logical Reasoning question:Prosecutor: I have furnished evidence that the accused committed the crime in question. The defense agrees that the crime did occur; they say that the accused did not commit the crime, but they have not proven that someone else did. Therefore, the jury should find that the defendant is guilty.

The reasoning in the prosecutor's argument is flawed because the argument

(A) ignores evidence that the accused might be innocent

(B) criticizes the arguments by the defense without addressing their flaws

(C) confuses the defense's failure to prove that someone else committed with proof that the accused is guilty

(D) implies that because the defense has admitted that the crime did occur, the defendant must be guilty

(E) fails to consider the possibility that someone else committed the crime

Note the structure: A paragraph that states the proposition — the argument — followed by a question asking something about the argument. Some Logical Reasoning questions are considerably longer than this one; few are shorter.

Some Logical Reasoning questions follow one argument with two questions. Most recent LSATs, though, haven't included many (or any) of these two-question arguments. Maybe people worked those questions too fast. Be prepared for Logical Reasoning sections that give one question for every argument, but if you come across an argument with two questions, don't fret about it; just answer it and enjoy the small reprieve. Think of it as a bonus — two questions for the price of one argument!

Questioning the argument

Following are some of the main types of Logical Reasoning questions you may encounter on the LSAT:

Assumptions: Which one of the following is an assumption required by the argument above?

Flaws: A reasoning flaw in the argument is that the argument . . .

Logical conclusions: Which one of the following most accurately expresses the main conclusion of the argument?

Strengthen: Which one of the following, if true, most strengthens the argument?

Weaken: Which one of the following, if true, most seriously weakens the argument above?

Support: Each of the following, if true, supports the claim above EXCEPT:

Role played by a claim: The claim that attorneys sometimes serve as their own secretaries plays which one of the following roles in the argument?

Resolving discrepancies or paradoxes: Which one of the following, if true, most helps to resolve the apparent paradox described above?

Patterns of reasoning: Which one of the following exhibits a pattern of reasoning most similar to that exhibited by the argument above?

Principles: Which one of the following conforms most closely to the principle illustrated by the statements above?